A typical residential/commercial heat exchanger assembly used in a heat pump system, or otherwise known as a heat exchanger coil, includes an inlet manifold, an outlet manifold, and a plurality of refrigerant tubes hydraulically connecting the manifolds for refrigerant flow from one manifold to the other. Corrugated fins interconnect adjacent refrigerant tubes to increase the available heat transfer area, as well as to increase the structural integrity of the heat exchanger coil. The refrigerant tubes and interconnecting corrugated fins together define the core of the heat exchanger. A heat exchanger coil may function in evaporator mode or condenser mode, depending on the needs of the heat pump system.
For heat exchanger coils operating in evaporator mode, the effects of momentum and gravity on a refrigerant entering the inlet manifold can result in the premature separation of the refrigerant into liquid and gas phases in the inlet manifold, thereby causing poor refrigerant distribution through the bank of refrigerant tubes. Non-uniform refrigerant distribution through the refrigerant tubes degrades the heat transfer efficiency between the refrigerant and a stream of air passing through exterior of the core, resulting in uneven temperatures over the core of the heat exchanger coil.
To assist in providing uniform refrigerant distribution through the refrigerant tubes, it is known to utilize distribution tubes in the inlet and outlet manifolds for the distribution and collection of refrigerant, respectively. A distribution tube disposed within the inlet manifold for uniformly distributing a two-phase refrigerant throughout the length of the inlet manifold is known as a distributor. Similarly, a distribution tube disposed within the outlet manifold for uniformly collecting the vapor refrigerant exiting the outlet ends of the refrigerant tubes is known as a collector.
The inclusion of distribution tubes in the manifolds of heat exchanger coils are costly in terms of the materials and labor required for the manufacturing of the distribution tubes, the increase in mass of the heat exchanger coils, as well as the time and labor required for the assembling of the distribution tubes into the manifolds. Accordingly, there remains a continued need for heat exchanger coils having cost effective distribution tubes.